<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container {
            width: 800px;
            margin: 20px auto;
        }
        
        header {
            width: 800px;
            height: 50px;
            background: #595959;
        }
        
        nav {
            width: 800px;
            height: 50px;
            background: #595959;
            margin-top: 10px;
        }
        
        .cont {
            overflow: hidden;
            margin-top: 10px;
        }
        
        article {
            float: left;
            width: 500px;
            height: 200px;
            padding: 40px 20px 20px;
            background: #595959;
        }
        
        aside {
            float: left;
            width: 250px;
            height: 260px;
            margin-left: 10px;
            background-color: #595959;
        }
        
        footer {
            width: 800px;
            height: 50px;
            background: #595959;
            margin-top: 10px;
        }
    </style>
</head>

<body>
    <div class="container">
        <header>header</header>
        <nav>nav</nav>
        <div class="cont">
            <article>article
                <section>section</section>
            </article>
            <aside>asaide</aside>
        </div>
        <footer>footer</footer>
    </div>
</body>

</html>